U.S. patent application number 17/618059 was filed with the patent office on 2022-09-29 for a method and a device for verifying liveness of a finger.
This patent application is currently assigned to PRECISE BIOMETRICS AB. The applicant listed for this patent is PRECISE BIOMETRICS AB. Invention is credited to Daniel GUSTAFSSON, Peter JOHNSON, Timothy SWYKA, Johan WINDMARK.
Application Number | 20220309827 17/618059 |
Document ID | / |
Family ID | 1000006394689 |
Filed Date | 2022-09-29 |
United States Patent
Application |
20220309827 |
Kind Code |
A1 |
SWYKA; Timothy ; et
al. |
September 29, 2022 |
A METHOD AND A DEVICE FOR VERIFYING LIVENESS OF A FINGER
Abstract
A method (700) for verifying liveness of a finger (102) of a
user by capturing a first fingerprint sample (402) from the finger
(102) placed on a display (104) by using a first sensor (106)
placed under the display (104). The method (700) may comprise
transmitting (702) light, by using a first light transmitting
display area of the display (104), towards a first area of the
finger (102), wherein the first light transmitting display area
(108) is smaller than a first sensor area; capturing (704)
reflected light from the finger (102) by the first sensor (104),
wherein the reflected light (114) is transmitted through the
display (104); and identifying (706) a first feature of the first
fingerprint sample (402) by using the reflected light (114),
wherein the first feature comprises scattered light from the finger
(102), wherein the light transmitted from the display (104)
comprises a first light component with a first wavelength from a
first area of the display (104).
Inventors: |
SWYKA; Timothy; (Potsdam,
NY) ; JOHNSON; Peter; (Potsdam, NY) ;
WINDMARK; Johan; (Lund, SE) ; GUSTAFSSON; Daniel;
(Lund, SE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PRECISE BIOMETRICS AB |
Lund |
|
SE |
|
|
Assignee: |
PRECISE BIOMETRICS AB
Lund
SE
|
Family ID: |
1000006394689 |
Appl. No.: |
17/618059 |
Filed: |
June 15, 2020 |
PCT Filed: |
June 15, 2020 |
PCT NO: |
PCT/EP2020/066469 |
371 Date: |
December 10, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
16443230 |
Jun 17, 2019 |
10984220 |
|
|
17618059 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G06V 40/1382 20220101;
G06V 40/1341 20220101; G06V 40/1365 20220101 |
International
Class: |
G06V 40/12 20060101
G06V040/12 |
Claims
1.-12. (canceled)
13. A method for verifying liveness of a finger of a user, the
method comprising: capturing a fingerprint sample from the finger
placed on a display by using a first sensor placed within or under
the display; extracting scattered light features from the
fingerprint sample; comparing the scattered light features with a
light scattering template; and if a match is found, generating a
liveness acceptance signal, else generating a liveness rejection
signal; wherein capturing the fingerprint sample involves
transmitting light of a first light component with a first
wavelength from the display towards the finger, and capturing light
reflected from the finger by the first sensor, wherein the
reflected light is transmitted through the display.
14. The method according to claim 13, wherein capturing the
fingerprint sample comprises: transmitting light, from a first
light transmitting display area of the display, towards the finger,
wherein the first light transmitting display area is divided into
subareas, wherein the light transmitted from the different subareas
comprises different light components with different wavelengths;
and capturing light reflected from the finger by the first sensor,
wherein the reflected light is transmitted through the display.
15. The method according to claim 13, wherein capturing the
fingerprint sample comprises: capturing a first fingerprint sample
by transmitting light of a first light component with a first
wavelength from the display towards the finger, and capturing light
reflected from the finger by the first sensor, wherein the
reflected light is transmitted through the display; capturing a
second fingerprint sample by transmitting light of a second light
component with a second wavelength from the display towards the
finger, and capturing light reflected from the finger by the first
sensor wherein the reflected light is transmitted through the
display; and generating the fingerprint sample from the first and
the second fingerprint samples as a composite fingerprint sample of
the first and the second fingerprint samples.
16. The method according to claim 13, further comprising:
determining a surrounding temperature and/or a surrounding
brightness; and determining the wavelength(s) to be used in the
step of transmitting light towards the finger based on the
surrounding temperature and/or the surrounding brightness.
17. The method according to claim 13, wherein the light scattering
template comprises information about how light with different
wavelength behave in the finger.
18. The method according to claim 17, wherein the light scattering
template further comprises information about how light with
different wavelength behave in different spoof-materials.
19. The method according to claim 13, wherein capturing the
fingerprint sample comprises illuminating only a part of the
finger.
20. A mobile device configured to verify liveness of a finger of a
user, the mobile device comprising: a display configured to
transmit light towards the finger placed on the display, wherein
the light includes a first light component with a first wavelength;
a first sensor placed under or within the display, wherein the
first sensor is configured to capture a fingerprint sample from the
finger placed on the display; and a processor configured to extract
scattered light features from the first fingerprint sample, compare
the scattered light features with a light scattering template, and
if a match is found, generate a liveness acceptance signal, else
generate a liveness rejection signal.
21. The mobile device according to claim 20, further comprising a
second sensor configured to determine a surrounding temperature
and/or a surrounding brightness; wherein the first wavelength is
determined based on the surrounding temperature and/or the
surrounding brightness.
22. The mobile device according to claim 20, wherein the light
scattering template comprises information about how light with
different wavelength behave in the finger.
23. The mobile device according to claim 22, wherein the light
scattering template further comprises information about how light
with different wavelength behave in different spoof-materials.
24. The mobile device according to claim 20, wherein the display is
configured to transmit light towards only a part of the finger
placed on the display.
25. A system configured to verify liveness of a finger of a user,
the system comprising a mobile device and a server; the mobile
device including a display configured to transmit light towards the
finger placed on the display, wherein the light comprises a first
light component with a first wavelength, and a first sensor placed
under or within the display, wherein the first sensor is configured
to capture a fingerprint sample from the finger placed on the
display, wherein the mobile device is configured to send the first
fingerprint sample to the server; the server including a control
unit, a transceiver, and a memory, wherein the server is configured
to execute an extraction function to extract scattered light
features from the fingerprint sample, and execute a comparison
function to compare the scattered light features with a light
scattering template, and if a match is found, generate a liveness
acceptance signal to the mobile device, else generate a liveness
rejection signal to the mobile device.
Description
TECHNICAL FIELD
[0001] The present patent application generally relates to the
field of biometric verification. More particularly, it is presented
a method for verifying authenticity of a finger of a user by
capturing a fingerprint sample from a finger by using a sensor
placed under a display and a system thereof.
BACKGROUND ART
[0002] Today, it is common practice to use fingerprint recognition
for verifying that a user of a mobile device is a legitimate user
of the device. From recently launched mobile phones, it is well
known to place a fingerprint sensor under the display of the mobile
device for verifying the authenticity of the user. Usually, this is
done by illuminate the finger with green light from the display and
then reflect the light to the sensor. By illuminate the finger with
light, energy is reflected by the finger and information related to
a fingerprint sample is captured. The information is compared to a
fingerprint template and the fingerprint recognition is verified as
a match or a non-match.
[0003] Due to that the fingerprint sensor is placed under the
display, instead of being placed next to the display, there is no
longer the same need to keep the fingerprint sensor small. When
having the fingerprint sensor placed next to the display, the
fingerprint sensor is preferably made as small as possible to
provide for that as little space as possible on a front side of the
mobile phone was needed to be set aside for the fingerprint
sensor.
[0004] Having the fingerprint sensor placed under the display may
result in that new algorithms for capturing the information related
to the fingerprint sample must be developed to make sure that
reliable and fast fingerprint recognition can be provided. For
instance, the reflected light from the finger is to pass the
display provided with light emitting elements before reaching the
fingerprint sensor, which may affect the reflected light. Further,
a glass as well as a protective film placed on the glass may also
be provided between the finger and the fingerprint sensor, which
further may affect the reflected light. In addition, to compensate
for that the reflected light may be affected on its way from the
finger to the fingerprint sensor in a different way than for
fingerprint sensor not placed under the display, algorithms for
determining liveness, i.e. whether the finger is real or fake, may
need to be adapted.
[0005] Today when assessing liveness it is known to involve texture
analysis combined by machine learning or deep learning based
methods that do image and/or texture analysis classification at
once.
[0006] Even if there are known solutions for placing a fingerprint
sensor under the display of a mobile device, there is still a need
to for methods and hardware arrangements that can ensure that the
authenticity of the user is determined reliably and fast.
SUMMARY
[0007] It is an object to at least partly overcome one or more of
the above-identified limitations of the prior art. In particular,
it is an object to provide a method that handles different
pressures more reliable and perform more secure and precise
fingerprint samples.
[0008] According to a first aspect it is provided a method for
verifying liveness of a finger of a user by capturing a first
fingerprint sample from the finger placed on a display by using a
first sensor placed under the display. The method may comprise:
[0009] transmitting light, by using a first light transmitting
display area of the display, towards a first area of the finger,
wherein the first light transmitting display area is smaller than a
first sensor area;
[0010] capturing reflected light from the finger by the first
sensor, wherein the reflected light is transmitted through the
display; and
[0011] identifying a first feature of the first fingerprint sample
by using the reflected light, wherein the first feature comprises
scattered light from the finger,
[0012] wherein the light transmitted from the display comprises a
first light component with a first wavelength from a first area of
the display.
[0013] By using the present method, verifying liveness of a finger
of a user may be performed in a more precise and secure manner.
Different materials have different light scattering and therefore,
by using the present method, it may be analyzed if the finger
placed on the display belongs to a living person or if it is
something else placed on the display.
[0014] The method may further comprise capturing a second
fingerprint sample by:
[0015] transmitting light, by using a second light transmitting
display area of the display, towards a second area of the
finger;
[0016] capturing reflected light from the finger by the first
sensor, wherein the reflected light is transmitted through the
display; and
[0017] identifying a first feature of the second fingerprint sample
by using the reflected light,
[0018] wherein the light transmitted from the display comprises a
second light component with a second wavelength from a second area
of the display.
[0019] The first light transmitting display area can be divided
into subareas, wherein the light transmitted from the different
subareas comprises different light component with different
wavelengths. The second light transmitting display area can be
divided into subareas, wherein the light transmitted from the
different subareas comprises different light component with
different wavelengths.
[0020] The step of transmitting light towards the first and/or
second area of the finger may comprise determining environmental
data for the user by using at least one second sensor; and adapting
the light based on the environmental data.
[0021] The step of identifying the first feature of the first
and/or second fingerprint sample may comprise generating a
composite fingerprint sample by using the reflected light from the
first and/or second light component.
[0022] The step of identifying the first feature of the first
and/or second fingerprint sample may comprise generating the
composite fingerprint sample by combining a plurality of generated
fingerprint samples, wherein each generated fingerprint sample
comprises different areas of the finger.
[0023] The method may further comprise identifying a second feature
of the first and/or second fingerprint sample from the finger by
using the reflected light, wherein the second feature of the first
and/or second fingerprint sample is based on a second feature area
of the first and/or second fingerprint sample, wherein the second
feature area is a subset of a first feature area of the first
and/or second fingerprint sample used for identifying the first
feature of the first and/or second fingerprint sample.
[0024] The method may further comprise extracting scattered light
features from the first fingerprint sample; retrieving a light
scattering template; comparing the scattered light features with
the light scattering template, and if a match is found, generating
a liveness acceptance signal, else generating a liveness rejection
signal.
[0025] The method may further comprise extracting fingerprint
features from the second fingerprint sample; retrieving a
fingerprint template; comparing the fingerprint features with the
fingerprint template, and if a match is found, generating a
fingerprint match acceptance signal, else generating a fingerprint
match rejection signal.
[0026] By using the present method, fingerprint recognition may be
performed in a more reliable and secure way since not only the
fingerprint sample is compared to a fingerprint template but that
also the scattered light is analyzed.
[0027] According to a second aspect, a mobile device configured to
capture a fingerprint sample from a finger of a user is provided.
The mobile device may comprise:
[0028] a display configured to transmit light towards the finger;
and
[0029] a first sensor placed under the display, wherein the first
sensor is configured to capture reflected light from the finger
according to the method according to the first aspect, wherein the
reflected light is transmitted through the display.
[0030] The mobile device may further comprise at least one second
sensor configured to determine environmental data for the user.
[0031] According to a third aspect it is provided a system
configured to verify liveness of a finger of a user. The system may
comprise:
[0032] a mobile device equipped with a display and a first sensor,
wherein the first sensor is placed under the display, the mobile
device is configured to: [0033] capture a first fingerprint sample
according to the first aspect; [0034] send the first fingerprint
sample to a server;
[0035] the server comprising a control unit, a transceiver, and a
memory, wherein the server is configured to: [0036] receive the
first fingerprint sample; [0037] receive a light scattering
template; [0038] execute an extraction function configured to
extract scattered light features from the first fingerprint sample;
[0039] execute a comparison function configured to compare the
scattered light features with the light scattering template, and if
a match is found, generate a liveness acceptance signal to the
mobile device, else
[0040] generate a liveness rejection signal to the mobile device.
Effects and features of the second and third aspects are largely
analogous to those described above in connection with the first
aspect. Embodiments mentioned in relation to the first aspect are
largely compatible with the second and third aspect. It is further
noted that the inventive concepts relate to all possible
combinations of features unless explicitly stated otherwise. A
further scope of applicability of the present invention will become
apparent from the detailed description given below. However, it
should be understood that the detailed description and specific
examples, while indicating preferred embodiments of the invention,
are given by way of illustration only, since various changes and
modifications within the scope of the invention will become
apparent to those skilled in the art from this detailed
description.
[0041] Hence, it is to be understood that this invention is not
limited to the particular component parts of the device described
or steps of the methods described as such device and method may
vary. It is also to be understood that the terminology used herein
is for purpose of describing particular embodiments only and is not
intended to be limiting. It must be noted that, as used in the
specification and the appended claim, the articles "a", "an",
"the", and "said" are intended to mean that there are one or more
of the elements unless the context clearly dictates otherwise.
Thus, for example, reference to "a unit" or "the unit" may include
several devices, and the like. Furthermore, the words "comprising",
"including", "containing" and similar wordings does not exclude
other elements or steps.
BRIEF DESCRIPTION OF THE DRAWINGS
[0042] Embodiments will now be described, by way of example, with
reference to the accompanying schematic drawings, in which
[0043] FIG. 1 generally illustrates a system for capturing a
fingerprint sample from a finger of a user.
[0044] FIG. 2 illustrates a cloud computer environment.
[0045] FIG. 3a-d illustrates different ratios between a first
sensor and a light transmitting display area of a display.
[0046] FIG. 4a-b generally illustrates a first and a second
fingerprint sample.
[0047] FIG. 5 generally illustrates a first and a second feature
area of a fingerprint sample.
[0048] FIG. 6a-b generally illustrates capturing a fingerprint
sample, wherein the finger is pressed against the display with
different pressure.
[0049] FIG. 7 illustrates a flow chart for verifying liveness of a
finger of a user.
DETAILED DESCRIPTION
[0050] With reference to FIG. 1, an overview of a system 100 for
capturing a fingerprint sample from a finger 102 of a user is
illustrated by way of example. The system 100 may comprise a mobile
device and a finger 102 of a user. The mobile device may be
equipped with a display 104 and a first sensor 106. According to
one example, the first sensor 106 may be placed under the display
104. According to another example, the first sensor 106 may be
placed within the display 104.
[0051] The display 104 may be configured to transmit light 112
towards the finger 102. Upon the user may place its finger 102 on
the display, a display area covered by the finger 102 may provide
the transmitted light 112 towards the finger 102. The display area
that may provide the transmitted light 112 is herein referred to as
a light transmitting display area 108. The whole display area, or a
subset of the display area, may be configured to act as the light
transmitting display area 108. The area of the finger 102 that may
be illuminated by the light is herein referred to as a finger area.
The light transmitting display area 108 may be smaller than the
finger area. Alternatively, or in combination, the light
transmitting display area 108 may be larger than the finger area.
Alternatively, or in combination, the light transmitting display
area 108 may be equal to the finger area. In other words, the
display 104 may be configured to transmit light 112 towards the
total finger area, or towards a subset of the finger area, based on
the size of the light transmitting display area 108.
[0052] The first sensor 106 may be configured to capture reflected
light 114 from the finger 102. The reflected light 114 may be
transmitted through the display 104. A total amount of the
reflected light 114, or a subset of the reflected light 114, may be
transmitted through the light transmitting display area 108. By way
of example, the first sensor 106 may be a fingerprint sensor.
[0053] Further, the mobile device may comprise a protective glass
110. The protective glass 110 may be placed on top of the display
104. Further, the protective glass 110 may in turn be provided with
a protective film, even though not illustrated, to further reduce a
risk of scratches. Both the protective glass 110 and the protective
film may affect the reflected light 114. Worth mentioning is also
that the protective glass 110 is in first hand optimized with
respect to the display 106 such that information displayed to the
user is presented in an appealing way.
[0054] FIG. 2 generally illustrates a cloud computer environment
200. The cloud computer environment 200 may comprise a mobile
device 202, a server 204, a database 206 and a network 208.
[0055] In addition to what have been discussed above, the mobile
device 202 may further comprise a processor 210 and a memory 212.
The mobile device 202 may be configured to capture a fingerprint
sample from a finger 102 of a user by using the first sensor 106.
According to an example, the mobile device 202 may be a mobile
phone. According to another example, the mobile device 202 may be a
smart card. The mobile device 202 may not be limited to these
examples but can be any kind of mobile device 202 configured to
capture the fingerprint sample. Further, the mobile device may
comprise at least a second sensor 214. By way of example, the
second sensor 214 may be configured to adjust the screen
brightness. By way of example, the second sensor 214 may be
configured to measure the outdoor temperature.
[0056] The server 204 may be configured to store the fingerprint
sample. The server 204 may be configured to receive and send
information from/to the mobile device 202 and/or the database 206.
Alternatively, or in combination, the database 206 may be
configured to store the fingerprint sample. The database 206 may be
configured to receive and send information from/to the mobile
device 202 and/or the server 204. The network 208 may be configured
to enabling the communication between the mobile device 202 and the
server 204. Alternatively, or in combination, the network 208 may
be configured to enabling the communication between the mobile
device 202 and the database 206. Alternatively, or in combination,
the network 208 may be configured to enabling the communication
between the server 204 and the database 206.
[0057] With reference to FIG. 3a-3d, a mobile device 202 equipped
with a display 104 and a first sensor 106 is illustrated by way of
examples. The display 104 may be configured to transmit light
towards a finger 102 of a user. The display 104 may comprise a
light transmitting display area 108 which is the part of the
display 104 that may provide transmitted light towards the finger
102. The transmitted light from the display 104 may comprise a
light component with a wavelength. The light transmitting display
area 108 may be divided into subareas of the light transmitting
display area 108. Different subareas may transmit the same light
component towards the finger 102. Alternatively, or in combination,
different subareas may transmit different light components towards
the finger 102. By the term different light components, it is meant
light components with different wavelengths, and hence, different
energy. Upon that may be the case, different parts of the finger
102 may be illuminated by different wavelengths. Thus, the
different wavelengths may penetrate differently depth into the
finger 102 and based on that, different information of the finger
102 may be captured.
[0058] An advantages by using different light components with
different wavelengths is that the body absorbs the energy of the
different wavelengths differently well and different energy can
penetrating into the skin with differently depth. Based on the
above, different and complementary information can be captured and
a more efficient and precise way of capturing fingerprint samples
is achieved.
[0059] The first sensor 106 may be configured to capture reflected
light from the finger 102. The first sensor 106 may be placed under
the display 104. The first sensor 106 may be placed within the
display 104. The first sensor 106 and the light transmitting
display area 108 may be fully or partly overlapping.
[0060] According to an example, as illustrated in FIGS. 3a and 3b,
the first sensor 106 is larger than the light transmitting display
area 108. The first sensor 106 and the light transmitting display
area 108 are of a circular shape. Neither the first sensor 106 nor
the light transmitting display area may be limited to be of the
circular shape. By using this arrangement, part of the reflected
light may travel through the light transmitting display area 108 to
the first sensor 106 while part of the reflected light may travel
beside the light transmitting display area 108, as illustrated in
FIG. 3b. This arrangement may be used when a subset of the finger
area may be illuminated. By using this arrangement, scattered light
from the finger may be captured in the fingerprint sample. Upon
comparing the scattered light with characteristics for scattered
light for fingers, a liveness verification of the finger may be
performed. Liveness verification may increase the security when
performing fingerprint recognition. Liveness verification of the
finger may be discussed more in detail in FIG. 4a-b and FIG. 7.
[0061] According to another example, as illustrated in FIGS. 3c and
3d, the first sensor 106 is smaller than the light transmitting
display area 108. By using this arrangement, all of the reflected
light may travel through the light transmitting display area 108 to
the first sensor 106, as illustrated in FIG. 3d. This arrangement
may be used when the whole finger area may be illuminated. By using
this arrangement, the fingerprint from the whole finger 102 may be
captured in the fingerprint sample.
[0062] Different ratio between the first sensor 106 and the light
transmitting display area 108 may provide different and
complementary information about the fingerprint sample.
Alternatively, or in combination, this may provide different and
complementary information about the ridges and/or valleys and/or
swirls of the finger. Capturing different fingerprint samples by
using different ratio between the first sensor 106 and the light
transmitting display area 108 and/or different light components may
provide a constitutive fingerprint sample comprising all
information in one sample.
[0063] With reference to FIG. 4a-b, a first and a second
fingerprint sample 402, 408 is illustrated by way of example.
[0064] According to the first fingerprint sample 402, only part of
the finger 102 may have been illuminated by the light. The first
fingerprint sample 402 may have a first fingerprint area. The first
fingerprint sample 402 may comprise a first fingerprint 404 and
scattered light 406 from the finger. The light may scatter
differently depending of the material the light is transmitting to
and reflected from. By way of example, upon there may be a piece of
spoof-material placed on the display instead of a real finger, the
scattered light may occur in a different manner in the fingerprint
sample 402 compared to upon there may be a real finger placed on
the display. By way of example, the spoof-material can be modeling
clay, glue or paper. The spoof-material is not limited to these
examples but can be any material used for creating fake
fingerprints. By analyzing the scattered light 406 of the
fingerprint sample, the authenticity of the liveness of the finger
may be analyzed. By way of example, the scattered light may be
compared to a light scattering template. The light scattering
template may comprise information about how different light, with
different wavelength, may behave in the finger 102. The light
scattering template may comprise information about how different
light, with different wavelength, may behave in the spoof-material.
If the comparison may be a match, the first fingerprint sample 402
may be a valid finger. Therefore, unlike today when machine
learning or deep learning is used, may this solution, for verifying
liveness of the finger, contribute to a more secure
verification.
[0065] According to the second fingerprint sample 408, the whole
finger may have been illuminated by the light. The second
fingerprint sample 408 may have a second fingerprint area. The
first fingerprint area may be a subset of the second fingerprint
area. The second fingerprint sample 408 may comprise a second
fingerprint 410. The first and second fingerprint sample 402, 408
may be illuminated by the same light component. Alternatively, or
in combination, the first and second fingerprint sample 402, 408
may be illuminated by different light components with different
wavelengths.
[0066] FIG. 5 generally illustrates a fingerprint sample 500 from a
finger 102 of a user. By way of example, the fingerprint sample 500
may be in line with the first or second fingerprint sample 402, 408
illustrated in FIG. 4a-b. The fingerprint sample 500 may comprise a
first feature area 502 and a second feature area 504. The second
feature area 504 may be a subset of the first feature area 502. The
first feature area 502 may comprise a first feature of the
fingerprint sample 500. The second feature area 504 may comprise a
second feature of the fingerprint sample 500. The second feature
may be a subset of the first feature.
[0067] The second feature area 504 may comprise information that
may need to be further analyzed. The second feature area 504 may
comprise information that may be characteristic for a specific
user. The system for capturing a fingerprint sample discussed above
may "learn the user" over time. The term learn the user should be
interpreted as the system know where the characteristics for the
specific user may be found in the fingerprint sample. Upon that may
be the case, the system may only capture spot-checks of the
fingerprint sample to verify the user.
[0068] FIG. 6a-b generally illustrates a system 600 for capturing a
fingerprint sample. The system 600 is in line with the system 100
discussed in FIG. 1.
[0069] In FIG. 6a, it is illustrated a finger 102 placed on the
display 104 with a pressure X. In FIG. 6b, it is illustrated the
finger 102 placed on the display 104 with a pressure Y. Herein, the
pressure X is smaller than the pressure Y. As a consequence, the
height of the finger 102 illustrated in FIG. 6a is larger than the
height of the finger 102 illustrated in FIG. 6b. The height of the
finger 102 illustrated in FIG. 6a is A and the height of the finger
102 illustrated in FIG. 6b is B, thus, A is larger than B.
[0070] Upon the user may press the finger 102 against the display
with a higher pressure, the density may be higher as well. As a
consequence, the energy, of the transmitted light, penetrating into
the finger 102 may penetrate deeper upon the density is higher.
[0071] Thus, the transmitted light may penetrate into the finger
102 differently depth based on the pressure from the finger 102 the
user may put against to display.
[0072] Upon the light penetrates differently deep into the finger
102, different information about the finger 102 may be
captured.
[0073] FIG. 7 is a flow chart generally illustrating an example of
a method 700 for verifying authenticity of a finger of a user by
capturing a first fingerprint sample 402 from the finger 102. The
first fingerprint sample 402 may be captured by using a first
sensor 106 placed under a display 104, wherein the user may place
the finger 102 on the display 104. The method 700 comprises the
following steps.
[0074] First, transmitting 702 light, by using a light transmitting
display area 108 of the display 104, towards a first area of the
finger 102. The light transmitting display area 108 may be smaller
than the area of the first sensor 106. The light transmitted from
the display 104 may comprise a first light component with a first
wavelength from a first area of the display 104.
[0075] Thereafter, capturing 704 reflected light from the finger
102 by the first sensor 106. The reflected light may be transmitted
through the display 104.
[0076] Then, identifying 706 a first feature of the fingerprint
sample 402 from the finger 102 by using the reflected light. The
first feature of the first fingerprint sample 402 may comprise
scattered light from the finger 102.
[0077] Optionally, the method 700 may comprise capturing a second
fingerprint sample 408. The second fingerprint sample 408 may be
captured by transmitting light, by using a second light
transmitting display area of the display 104, towards a second area
of the finger 102. Then, capturing reflected light from the finger
102 by the first sensor 106, wherein the reflected light is
transmitted through the display 104. Thereafter, identifying a
first feature of the second fingerprint sample 408 by using the
reflected light. The light transmitted from the second light
transmitting display area may comprise a second light component
with a second wavelength from a second area of the display. The
first and second light component may be the same light component
with the same wavelength. Alternatively, or in combination, the
first and second light component may be different light components
with different wavelengths.
[0078] Further, the step of transmitting 702 light may comprise
determining environmental data for the user. The environmental data
may be determined by using at least one second sensor 214. Based on
the environmental data, the transmitted light may be adapted.
[0079] The step of identifying 706 the first feature of the first
and/or second fingerprint sample 402, 408 may comprise generating a
first and/or second composite fingerprint sample by using the
reflected light from the first and/or second light component.
Alternatively, or in combination, the step of identifying 706 the
first feature of the first and/or second fingerprint sample 402,
408 may comprise generating the first and/or second composite
fingerprint sample by combining a plurality of generated
fingerprint samples. Each of the generated fingerprint sample may
comprise different areas of the finger.
[0080] Alternatively, or in combination, the method 700 may further
comprise identifying a second feature of the first and/or second
fingerprint sample 402, 408 from the finger 102 by using the
reflected light. The second feature of the first and/or second
fingerprint sample 402, 408 may be based on a second feature area.
The second feature area may be a subset of a first feature area,
wherein the first feature area may be used for identifying the
first feature of the first and/or second fingerprint sample.
[0081] Alternatively, or in combination, the method 700 may further
comprise extracting scattered light features from the first
fingerprint sample 402. Retrieving a light scattering template.
Thereafter, comparing the scattered light features with the light
scattering template and if a match is found, generating a liveness
acceptance signal, else generating a liveness rejection signal. The
light scattering template may comprise information about how
different light, with different wavelength, may behave in the
finger 102. The light scattering template may comprise information
about how different light, with different wavelength, may behave in
different spoof-materials.
[0082] Alternatively, or in combination, the method 700 may further
comprise extracting fingerprint features from the second
fingerprint sample 408. Retrieving a fingerprint template.
Thereafter, comparing the fingerprint features with the fingerprint
template, and if a match is found, generating a fingerprint match
acceptance signal, else generating a fingerprint match rejection
signal.
[0083] From the description above follows that, although various
embodiments of the invention have been described and shown, the
invention is not restricted thereto, but may also be embodied in
other ways within the scope of the subject-matter defined in the
following claims.
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